Device and method for accurately supplying components of an automatic gearbox for motor vehicles

ABSTRACT

The device for accurately supplying components of an automatic gearbox for motor vehicles is characterized in that the supply line which supplies the gearbox with hydraulic oil is divided into two lines ( 1, 2 ), the first line ( 1 ) having an aperture ( 4 ) and a differential pressure valve ( 5 ) and the second line ( 2 ) having a pressure limiting valve ( 6 ).

[0001] The present invention relates to a device designed to ensure aprecisely targeted fluid supply to components of a vehicle automatictransmission, especially a friction-type transmission, and acorresponding method.

[0002] Continuously variable, friction-type transmissions are ordinarilyequipped with input and output disks that are oriented coaxially to acommon shaft and are arranged in pairs, the inner surfaces of which aretoroidal in shape, along with friction gears that are positioned betweenthe pairs of input and output disks. These friction gears are infrictional contact with both the input and the output disks, andtransfer torque that is supplied to them by the input disks to theoutput disks via the frictional contact, wherein the speed of thefriction gears is higher the greater the distance is between their pointof contact with the input disk and the rotational axis. In contrast, thespeed of the output disk is greater, the closer the point of contact,between the friction gear and the output disk, is to the rotational axisis. Hence, by swiveling the friction gears, the speed of the output diskis infinitely adjustable. To this end, the rotational axes of thefriction gears are mounted on a carrier, which can be controlled via aswiveling device.

[0003] If this type of friction transmission is connected to an internalcombustion engine of a vehicle, via a hydrodynamic converter or a wetrunning starting clutch, then the clutch will generate heat, during slipdrive which must then be removed via a purposeful supply of hydraulicfluid.

[0004] However, the operating points for cooling the starting clutch andfor cooling and lubricating the remaining transmission components—inother words the bearing and the teething—are very different, so that thehydraulic fluid which is available and supplied to the automatictransmission must be supplied in varying quantities to the startingclutch and to the remaining components of the transmission.

[0005] The object of the present invention is to disclose a device and amethod with which lubricating fluid can be optimally and preciselysupplied to the components of an automatic transmission, especially afriction-type transmission, wherein, compared with traditional devicesand/or methods, a substantially lower overall quantity of hydraulicfluid is required.

[0006] Proceeding from a device of the type described in detail above,this object is attained with the features specified in thecharacterizing section of claim 1; advantageous designs are described inthe sub-claims; the method specified in the invention is outlined ingreater detail in the independent method claim.

[0007] The device designed, according to the invention, for a preciselytargeted supply to components in an automatic vehicle transmission thusprovides that the feed line that supplies the transmission withhydraulic fluid is separated into two lines; one line is equipped with arestrictor and a differential pressure valve oriented in the directionof flow, while the other is equipped with a pressure relief valve.

[0008] The differential pressure valve is advantageously connected to anelectric pressure controller, which itself is connected to theelectronic transmission control system; in another advantageousexemplary design, the pressure relief valve is also connected to theelectric pressure controller.

[0009] According to the method specified in the invention for theprecisely targeted supply to components in an automatic transmission,especially a friction-type transmission for a vehicle, the hydraulicfluid that is supplied to the transmission for the purpose oflubricating and cooling is separated in two lines into twosub-quantities. In the first line, the rate of flow is controlled via arestrictor and a differential pressure valve, both of which areinstalled within this line, while in the second line, the pressure inthe first line prior to the restrictor is controlled via a pressurerelief valve installed within this second line. The differentialpressure valve in the first line regulates the differential pressure atthe restrictor that is installed in the same line. By preciselyregulating the differential pressure valve, via a control valve in theform of an electric pressure controller which itself is connected to theelectronic transmission control system, the flow rate can be controlledin the first line that is equipped with the restrictor and thedifferential pressure valve. The remaining hydraulic fluid flows throughthe second line and is fed to the transmission components, for example,to the bearings.

[0010] The advantage of the device specified in the invention is thatthe quantity of hydraulic fluid that is required for purposes of coolingand lubrication can be substantially reduced, allowing a savings ofabout 50% over traditional automatic transmissions. The precise controlof the amount of hydraulic fluid in the first line, which is equippedwith the restrictor and the differential pressure valve, enables thecontrol and maintenance of a predetermined temperature of someheat-producing points in the automatic transmission, especially thestarting clutch. Despite a decrease in hydraulic power—in other wordsthe losses that occur in an automatic transmission—the advantage ofreduced power consumption by the hydraulic fluid used for lubricatingpurposes is still achieved. The resolution and hysteresis of thecharacteristic flow rate curve also more advantageously compares withthat of a traditional automatic transmission.

[0011] Below, the invention will be described in greater detail withreference to the attached diagrams, in which two advantageous exemplarydesigns of a device as specified in the invention are schematicallyillustrated. These show:

[0012]FIG. 1 is a first hydraulic fluid cycle, and

[0013]FIG. 2 is a second hydraulic fluid cycle, according to theinvention.

[0014] In the diagrams, similar components are designated with the samereference numbers. A feed line for hydraulic fluid in an automatictransmission, which in this case is a friction-type transmission, isdesignated with the numeral 3. The feed line 3 is divided into two lines1, 2 for a precisely targeted supply to the components of the automatictransmission, which require different operating points for coolingand/or lubrication. To this end, a restrictor 4 and a differentialpressure valve 5 are installed in the first line 1, while a pressurerelief valve 6 is installed in the second line 2.

[0015] The differential pressure valve 5, in the first line 1, isconnected to an electric pressure controller 7, which is itselfconnected to the electronic transmission control system 8, by which itis controlled in keeping with the required operating parameters.

[0016] In the exemplary design illustrated in FIG. 2, the pressurerelief valve 6 in the second line, is also connected, via the dashedline 9, to the electric pressure controller 7 and thus to the electronictransmission control system 8.

[0017] Thus, with the arrangement described, the hydraulic fluidrequired by the automatic transmission is divided into twosub-quantities and is fed through the lines 1 and 2, wherein in thefirst line 1 the flow rate can be precisely controlled via therestrictor 4 and the differential pressure valve 5. In this process, thedifferential pressure valve 5 generates a differential pressure at therestrictor 4, wherein the differential pressure valve 5 is controlledvia the electronic transmission control system 8 and the electricpressure controller 7. This enables a precise control of the flow ratein the line 1, which is connected to the heat-generating starting clutchof the friction-type transmission.

[0018] The remaining hydraulic fluid flows through line 2 and serves tolubricate the bearing and/or the teething, wherein the pressure reliefvalve 6, provided in the second line 2, controls the pressure prior tothe restrictor 4. If the pressure relief valve 6 is also controlled bythe electric pressure controller 7, and thus by the electronictransmission control system 8, via the line 9 as shown in FIG. 2, thenthe pressure in the first line 1 can also be controlled prior to therestrictor.

[0019] The precise control of the quantity of hydraulic fluid in thefirst line 1 for the purpose of regulating a preset temperature atheat-generating points in the automatic transmission makes it possibleto reduce the overall quantity of hydraulic fluid required by thetransmission by approximately 50%. Lower power consumption in thegeneration of lubricating pressure also results.

REFERENCE FIGURES

[0020] Reference FIGS. 1 Line 2 Line 3 Feed Line 4 Restrictor 5Differential Pressure Valve 6 Pressure Relief Valve 7 Electric PressureController 8 Electronic Transmission Control System 9 Line

1. Device for the precisely targeted supply to components in anautomatic vehicle transmission, characterized in that feed line (3) thatsupplies the transmission with hydraulic fluid is divided into two lines(1, 2), wherein a restrictor (4) and a differential pressure valve,(5)are installed in the first line (1), and a pressure relief valve (6) isinstalled in the second line (2).
 2. Device according to claim 1,characterized in that the differential pressure valve is connected to anelectric pressure controller (7), which is connected to the electronictransmission control system (8).
 3. Device according to claims 1 and 2,characterized in that the pressure relief valve is connected to theelectric pressure controller (7).
 4. Method for the precisely targetedsupply to components in an automatic vehicle transmission, characterizedin that the hydraulic fluid that is supplied to the transmission via afeed line for the purpose of lubricating and cooling is divided into twosub-quantities, which flow through two separate lines, wherein in thefirst line the flow rate of the hydraulic fluid is controlled via arestrictor and a differential pressure valve, which is controlled by anelectric pressure controller, which itself is controlled by theelectronic transmission control system, while the pressure prior to therestrictor in the first line is controlled via a pressure relief valveinstalled in the second line, which also is controlled by the electricpressure controller and thus by the electronic transmission controlsystem.